1. Technical Field
The disclosure concerns centering and rotationally orienting a workpiece, such as a semiconductor wafer, in a factory interface.
2. Background Discussion
A workpiece such as a semiconductor wafer is transported to a workpiece support in a tool such as a reactor chamber or process chamber, using a factory interface. The factory interface has at least one load port for receiving a workpiece to be processed and a load lock providing a transition between the atmospheric environment of the factory interface and the vacuum environment of the tool or process chamber. Workpieces are transported within the factory interface between the load port and the load lock by a factory interface (FI) robot. The workpiece must be oriented correctly (by rotation) before it is transferred to the tool or process chamber. This requires an aligner (or “orienter”) within the factory interface to rotate the workpiece to the orientation required by the tool or process chamber. For this purpose, the FI robot grabs a workpiece to be processed from the load port and places it on the aligner in the factory interface, and then releases the workpiece. The aligner may use a standard notch on the workpiece edge to orient the workpiece. The term orientation or orientation of the workpiece refers to a rotational position of the workpiece about a central axis of symmetry of the workpiece.
After the aligner has oriented the workpiece, the FI robot grabs the workpiece, lifts it from the aligner and transports it to the load lock, where it releases the workpiece. A vacuum robot in the load lock then transports the workpiece to the workpiece support stage of the tool or process chamber.
One problem is that the aligner takes about four seconds to properly align each workpiece. This imposes a significant limitation on productivity or throughput. Another problem is that the FI robot must handle (by either grabbing or releasing) each workpiece four times, in accordance with the foregoing description in which it delivers the workpiece first to the aligner and then to the load lock. With the current reductions in workpiece (wafer) thickness, and with circuit structures using more of the workpiece surface and thereby pushing integrated circuit features closer to the workpiece edge, thin film structures at the workpiece edge are more susceptible to damage from repeated handling by the FI robot. The repeated handling by the FI robot involves greater risk of damage to thin film structures on the workpiece.